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Polyvinylidene fluoride microporous membrane prepared by gel extrusion casting method

A technology of melt extrusion and process method, which is applied in the field of polyvinylidene fluoride microporous film preparation by gel extrusion casting method, can solve the problems of large solvent volatilization and low solid content, and achieve low solvent consumption and solid The effect of high content and uniform film formation

Inactive Publication Date: 2017-10-31
BEIJING UNIV OF CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0015] The above-mentioned methods for preparing PVDF microporous membranes are all solution methods, and the amount of solvent used is 70-90%.

Method used

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  • Polyvinylidene fluoride microporous membrane prepared by gel extrusion casting method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Add 2 kg N,N-dimethylacetamide (DMAC) to 10 kg PVDF, and stir at room temperature to form a uniform gel. After that, the gel is added to the metering feeder of the extruder, plasticized and melted in the screw extruder at 200-215°C, and cast through the die on a steel belt rotating at a constant speed at 80°C. Membrane, steel belt speed is 3 rev / min. After the continuously heated steel strip is dried, it is wound up into a film by a winder, and finally the finished microporous film is obtained. The thickness of the film is 20 µm, and the thickness tolerance in the longitudinal and transverse directions is less than 0.5 µm. The pore size of the micropores is 2-5 µm, the porosity is 43%, and the water flux under the pressure of 0.1 MPa is 180 L / m2•h.

Embodiment 2

[0036] Add 2 kg N, N-dimethylformamide (DMF) to 10 kg PVDF, and stir at room temperature to form a uniform gel. After that, the gel is added to the metering feeder of the extruder, plasticized and melted in the screw extruder at 200-215°C, and cast through the die on a steel belt rotating at a constant speed at 70°C. Membrane, steel belt speed is 3 rev / min. After the continuously heated steel strip is dried, it is wound up into a film by a winder, and finally the finished microporous film is obtained. The thickness of the film is 20 µm, the thickness tolerance in the vertical and transverse directions is less than 0.5 µm, the pore size of the micropore is 2-5 µm, the porosity is 40%, and the water flux under the pressure of 0.1MPa is 175L / m2•h.

Embodiment 3

[0038] Add 2 kg of N-methylpyrrolidone (NMP) to 10 kg of PVDF, and stir at room temperature to form a uniform gel. Then the gel is added to the metering feeder of the extruder, plasticized and melted and extruded in the screw extruder at 200-215 ° C, and cast on a steel belt rotating at a constant speed of 100 ° C through the die die. Membrane, steel belt speed is 3 rev / min. After being dried by the continuously heated steel strip, it is wound up into a film by a winder, and finally the finished microporous film is obtained. The thickness of the film is 20 µm, the thickness tolerance in the vertical and transverse directions is less than 0.5 µm, the micropore diameter is 2-5 µm, the porosity is 50%, and the water flux under the pressure of 0.1MPa is 195 L / m2•h.

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Abstract

The invention provides a polyvinylidene fluoride microporous membrane prepared by a gel extrusion casting method and relates to a technique. The technique is characterized in that polyvinylidene fluoride resin and a certain quantity of a solvent are mixed to be gel-like, then the gel-like mixture is added into an extruder (2) through a feeder (1) to be molten and extruded, after that, casting membrane-forming is performed on a roller or a steel belt (5), which is continually heated and rotates at a constant speed, through a die neck mold (3), and coiling membrane-forming is performed by a winder (9) after drying to finally obtain a microporous membrane end product. The steel belt is heated through blowing, and air enters air inlets (6 and 7), is heated, passes through a casting machine, and then is discharged out through air outlets (4 and 8). The polyvinylidene fluoride microporous membrane has the characteristics that the solid content of a gel in the extruder is high, evaporation of the solvent is less, and accordingly, air pollution is less; in addition, as molding, drying and shaping are performed simultaneously in the membrane preparation process, the membrane forming rate and the membrane efficiency are high; the membrane preparation process is simple and flexible; and the membrane is good in flatness, uniform and adjustable in thickness and high in mechanical performance.

Description

technical field [0001] The invention relates to a process for preparing a polyvinylidene fluoride microporous membrane by a gel extrusion casting method, and belongs to the field of polymer processing. Background technique [0002] Polyvinylidene fluoride (PVDF) is a fluorocarbon thermoplastic resin with excellent performance, which has outstanding solvent resistance, acid and alkali resistance, oxidation resistance, weather resistance and chemical stability. The PVDF film will not be brittle or cracked after being placed outdoors for one or two decades, and its performance will basically remain unchanged after being irradiated with an ultraviolet lamp with a wavelength of 20-400 nm for one year. PVDF can only be dissolved or partially dissolved in a few solvents such as oleum, strong alkali and dimethylformamide (DMF), and is not corroded by acids, alkalis, strong oxidants and halogens at room temperature. The difference between the melting point (about 170°C) and the deco...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B29D7/01B29K27/00
CPCB29D7/01B29K2027/16
Inventor 贺建芸康维嘉赵长松苑会林杨大伟刘振文罗锡丹李嘉维杨卫民丁玉梅
Owner BEIJING UNIV OF CHEM TECH
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